To this end, the invention has for its object a process for de-icing an air intake cowling of a reaction motor, comprising an air inlet lip, a system for de-icing the lip supplied with warm fluid under pressure, and means for acoustic attenuation forming an integral portion of a predetermined region of said lip, characterized in that it consists in constituting said acoustic attenuation means by separate islands each formed by a sandwich comprising an acoustically resistive porous layer forming a portion of the external envelope of the fan channel delimited by said air intake lip, a single or multi-layer porous cellular core, and a reflector, constituting or covering the reflector of each island with a common element extending over all the islands, placing in communication the space or spaces between the islands, on the one hand, with the interior of the lip and, on the other hand, with the exterior of the cowling so as to create forced circulation of the de-icing fluid from the interior of the lip to the exterior of said cowling via the space or spaces between islands.
The de-icing function of the air intake lip, particularly in line with the blower channel, where the acoustic attenuation structure is located, is efficaciously produced by the flow of warm fluid which, thanks to the pressure difference between the interior of the lip and the exterior of the air intake cowling, is made to sweep through the space or spaces between the islands, delimited between the internal wall of the lip and the element covering the assembly of the cellular structure, through one or several openings provided on a section of said structure, to exit through one or several outlet openings, for example provided opposite the intake openings, the outlet openings being connected by one or several conduits to one or several openings for escape to the exterior of the cowling, by the de-icing fluid.
The de-icing fluid is, during the passage through said space or spaces between islands, made to bathe the internal surface of the internal wall of the lip that is not covered by the islands.
Effective de-icing is thus ensured at the height of the internal wall of the lip and without the rejection of de-icing fluid into the fan channel because where the fluid bathes said wall, there is no communication with the outside of the lip, the wall of this latter at this place not being porous.
Increased de-icing is moreover performed by said porous surfaces of the islands, which bathe in the warm fluid, by conduction or through the cellular structure.
The islands can have different structures and be constituted by juxtaposed strips of a honeycomb material or of juxtaposed tubular lugs perpendicular to the wall of the air intake lip.
The invention also has for its object a device for deicing an air intake cowling, produced according to the above process, comprising an air intake lip, means for injecting into the lip a warm de-icing fluid under pressure, acoustic attenuation means forming an integral portion of a predetermined region of said lip and means for evacuating to outside the cowling the de-icing fluid, characterized in that said acoustic attenuation means are constituted by separate islands each formed of a sandwich comprising an acoustically resistive porous layer forming a portion at least of the internal wall of the lip, a central cellular core and a reflector, said reflector being constituted by a common element extending over all the islands whilst the islands are arranged so as to permit the passage of the de-icing fluid through the spaces between islands, said de-icing device moreover comprising a chimney device connecting said spaces between islands to the external wall of the air intake cowling.
According to one embodiment, said islands are constituted by tubular lugs disposed in an annular region of the lip and arranged such that the spaces between the lugs will be, on a flank of said zone, in communication with the interior of the lip, and, on the other flank of said zone, in communication with a space connected to said chimney device.
According to another embodiment, said islands are constituted by strips of honeycomb cores defining between them corridors, arranged in an annular region of the lip and arranged such that said corridors will be, on one flank of said zone, in communication with the interior of the lip, and, on the other flank of said zone, in communication with a space connected to said chimney device.
According to still another embodiment, said islands are in the shape of strips disposed parallel to the lip and arranged such that at at least one of their ends, the corridors between bands will be in communication with the interior of the lip, said chimney device being connected to said corridors at their other end or at a point located between the two ends.